Propulsion and control system for motorboat

ABSTRACT

A combination motor boat propulsion and steering control system is shown which is particularly adapted to planing hull, high speed boats. The invented combination will eliminate the need for a rudder in such craft by providing dual variable pitch propellers, differentially pitch controlled for steering, and provides for water contact only up to the hubs of counterrotating propellers, thereby minimizing drag. Forward-reverse control and optimized speed control (while maintaining high power transfer efficiency) are effected by superimposed separate control of propeller pitches together in the same sense.

United States Patent 1191 Marco et al. 1 Jan. 9, 1973 154] PROPULSIONAND CONTROL SYSTEM 3,113,549 12/1963 Frank et al. ..115/37 FOR MOTORBOAT3,598,080 8/1971 Sheilds ..115/14 [75] Inventors: Alex A. Marco, 2556 N.Strathmore Avenue, Rosemead, Calif. 91770; 5"."f n i g g Dennis L.Wirth, 624 North Reese an a frf f u e ge PL, Burbank, Calif. 91501 0[73] Assignee: said Marco and Wirth, part interest [57] ABSTRACTv toeach A combmation motor boat propulslon and steering Filedi J y 1970control system is shown which is particularly adapted [21] APP] No:57,296 to planing hull, high speed boats. The invented combmatlon w1llelimmate the need for a rudder 1n such craft by providing dual variablepitch propellers, dif- [52] US. Cl ..115/35 ferentiany pitch controlledfor Steering, and provides [51 lit. Cl. f water Contact ly p t th h b ft t [58] Fleld of Search ..1 l 5/35, 34 R, 34 C, 37 ing propane, therebyminimizing drag Forward reverse control and optimized speed control(while [56] References C'ted maintaining high power transfer efficiency)are ef- UNITED STATES PATENTS fected by superimposed separate control ofpropeller pitches together in the same sense. 2,369,456 2/1945 Hammond,Jr ..115/35 803,671 11/1905 Curtis ..115/34 C 5 Claims, 4 DrawingFigures PATENTED JAN 9 I973 SHEET 1 BF 3 FIGURE l INVENTORS ALEX A.MARCO DENNIS L.W|RTH am ,ZTW

AGENT PATENTEDJMI 9 I876 SHEET 2 [IF 3 F'GURE 2 INVENTORS ALEX A. MARCODENNIS 1.. WIRTH BY MLZUM AGENT PAIENTEDJIII 9|975 3,709,187

SHEET 3 0F 3 22 4 2| 20 I8 I? 3 l6 STERN TBOW 42 h T\ I 43 34 SECTIONA-A FIGURE 3b INVENTORS ALEX A. MARCO DENNIS L.WIRTH M 524 M AGENTPROPULSION AND CONTROL SYSTEM FOR MOTORBOAT This invention relates toaquatic vehicles, and more particularly to power propelled boats. It ismost useful in connection with a speed boat having a planing hull.

it is normally considered necessary for speed boats" to make use of theplaning principle as contrasted from the principle of the displacementhull upon which larger vessels ordinarily depend. In connection with aplaning hull it will be noted that there is no appreciable depth to thekeel section of the boat and use is made of the fact that such a boatplanes across the surface of the water over a cushion of water mixedwith air bubbles. The familiar hydrofoil which is frequently driven byan air contact propeller is one approach to solving the problem ofminimizing the drag introduced by rudders, propeller shafts, propellerhubs, and other structural and functional members which project downwardinto the water.

As compared to a hydrofoil driven by an air propeller the presentinvention provides a much more efficient and less expensiveconfiguration. Obviously the air propeller drive is also a cumbersomeandinherently dangerous device which tends to apply the forward thrustto the boat too far above the water line to be optimum. The presentinvention obviates the disadvantages of this type of boat drive, and ascompared to the more conventional inboard and outboard motor boatconfigurations the following is to be noted.

Both inboard and outboard prior art motor boat propulsion systemsrequire the use of drag producing members which project into the water.An outboard motor necessarily loses a large portion of its gross forwardthrust end power efficiency because of the drag caused by the shafthousing, hub, skeg, and exhaust, all of which project downward into thewater below the transom of the boat.

Conventional propellers used in the prior art inboard and outboard motorboat configurations are also relatively inefficient due to the largedifference in speed between the blade tip and the portion of the bladenearest the center of rotation. Such conventional propellers, moreover,are necessarily thicker nearest the hub for structural reasons, and thisresults in a further loss of thrust producing capability. The presentinvention also tends to abviate another of the more familiardisadvantages of the conventional inboard or outboard motor boatconfiguration. This is the fact that the position of the propeller is,in these prior art situations, lower than is desirable for theproduction of maximum planing efficiency. In accordance with the presentinvention it will be seen that the net location of the forward thrustvectors is very nearly in line with the watercontact surface of aplaning hull, which is a great advantage from the point of view ofmaximum power efficiency through a more efficient thrust transfer.

The present invention moreover eliminates many of the conventional partsof prior art motor boat propulsion systems while providing suchincreased thrust efficiency and much greater operational flexibilityincluding dock maneuvering and power braking.

In comparing the present invention with the usual prior art inboardmotor boat it will be noted immediately that the present inventioneliminates the need for clutching, shaft log, rudder, rudder packinggland, propeller shaft, and propeller shaft strut. Notwithstanding theelimination of these parts it will be shown that the configuration ofthe present invention is more efficient and maneuverable than any priorart signle or double propeller inboard motor boat configuration.

As compared to the usual prior art outboard motor boat arrangement, itwill be noted that the present invention eliminates the outboard shafthousing, the out board hub housing, the skeg, and the outboard exhaustpipe.

The present invention moreover provides the advantage which would accruefrom the use of a torque converter or a multispeed transmission, in thatthe adjustable pitch of the propeller blades according to the presentinvention provides the ability to match engine speed and torque tovarious boat load and speed conditions such that optimum throttle andpitch settings can be found for every condition.

It may be said that the general objective of the present invention isthe provision of a motor boat propulsion system which has all theadvantages of the prior art conventional inboard motor boat system whilemaintaining and even improving upon the flexibility and maneuverabilityafforded by the usual prior art outboard motor boat system. In additionit is an objective of the present invention to provide increased powerand thrust efiiciency and simple but very effective poser braking. Thsesand other advantages of the present invention will be obvious as thedescription proceeds with reference to the drawings.

For clarity in the elucidation of the present invention drawings areprovided as follows.

FIG. 1 illustrates pictorially the assembled elements typical of theinvention.

FIG. 2 illustrates pictorially the details of the typical arrangementfor providing variable propeller blade pitch in accordance with thepresent invention.

FIG. 3 a and 3 b illustrate partial sectional views of the propellerdrive and pitch control mechanisms.

Referring now to FIG. 1 it will be noted that a relatively conventionalmotor boat hull is illustrated. The transom or stem section of the hullis shown as a flat substantially vertical member although this and theother specific details of the hull shape are arbitrarily selected forillustration and substantial variations will be seen to be possible asordinary engineering design option. It will be noted that the depth ofthe keel as illustrated at 2 is minimal, which is typical of planingtype hulls which are most useful in combination with the presentinvention. lt will be noted that a pair of propeller assemblies 3 and 4are mounted by means of straightforward shaft and bushing arrangements(not visible in HO. 1). For each of the propeller assemblies 3 and 4 adirection of normal rotation which may correspond to forward motion ofthe hull or reverse motion (depending upon the specific pitch of theblades of the two propeller assemblies) is illustrated by means ofrotational arrows. It will be noted that the two propeller assembliescounter-rotate. This is necessary particularly at high power levelscorresponding to high speeds, since the placement of the two propellerassemblies is such that only the blades themselves are in contact withthe water at or near the bottom of their travel when the boat is in thefull planing mode of operation. Thus the hubs and internal hubmechanisms of the two propeller assemblies 3 and 4 remain substantiallyout of the water, except at lower or idling speeds when some settling ofthe hull into the water is normal. A single propeller or two propellersrotating in the same direction would necessarily produce a large sidethrust which would obviously be undesirable.

In FIG. 1 the boat transom 1 is partially cut away to expose the gearcase 5 mounted just inside the transom. A conventional engine 6withconventional engine accessories such as an air cleaner 7, manifold8, etc. is illustrated for driving the gear box 5 in a manner which willbe more fully described as the description proceeds. A conventionalstearing wheel 25 operates in connection with a wind-unwind drum andcables 10 and 12 which'operate in conjunction with the pitch controlyoke 9 to differentially vary the pitches of the two propellers as willbe more fully described in connection with a later figure. Cable 11 willbe seen to be associated with lever 13 to vary the pitches of the twopropellers in the same sense at the same time (i.e. to increase ordecrease the bite" of the two propellers at the same time). Theslideable bearing 29 will be described more fully in connection with alater figure.

It will be noted the the propeller blades 15, 16, 17 and 18 for thepropeller assemblies 3 are shown pitched for forward motion when thepropeller assembly is rotating as shown by the rotational arrows.Similarly blades 19, 20, 21 and 22 on propeller assembly 4 are pitchedfor forward motion in view of the arrows of rotation. Propeller hubmechanisms 23 and 24 are designed to control all the blades of eachpropeller simultaneously. The control cables of which 10, 11 and 12 aretypical are supported'by drilled blocks such as 14 in a conventional andwell known way.

Referring now to FIG. 2 propeller assembly 3 has been chosen fordiscussion, however this is an arbitrary choice asthe description willbe seen to apply equally well to propeller assembly 4. A ribbeddisc 23which has its ribbed ends formed into racks of which 26 is typical is incontact with pinion gears, one to each root shaft of the variable pitchblades 15,16, 17 and 18. In operation the entire assembly of FIG. 2rotates and the ribbed disc 23 is only capable of moving with respect tothe housing of the propeller assembly 3 along an axial direction forvarying blade pitches, in response to the control cables. The ribbeddisc 23 is however not permitted to rotate with respect to the housing 3of the propeller assembly since it is necessary that the rack gears, ofwhich 26 is typical, should always remain in firm contact with thepinion gears of which 28 is typical. ln affixing the pinion gears suchas 28 to the propeller root shafts such as 27 a keyed arrangement orsome other arrangement known in the mechanical arts which is equallyresistant of the reaction torque exerted onthe shaft 27 by blade such asas it makes high speed contact with the water is necessary. Referringnow to FIGS. 3a and 3b, these partial sectional views will be describedand referred to together for clarity.

FIG. 3b is a sectional view-of the gearing in the gear box 5 looking tothe rear as depicted by the section out line in FIG. 3a. It will beobvious from FIG. 3b that the four meshed gears 34, 35, 37 and 39provide a convenient way of obtaining the necessary counter-rotation ofthe two propeller assemblies 3 and 4. In FIG. 3b typical blades 15 and19 will be seen projecting below the bottom surface of the hull into thewater thus providing thrust vectors which are very nearly in the planeof the hull bottom. In the configuration shown the application of powercould be made either to shaft 36 or shaft 38 making gear 35 or gear 37the primary driven geai. Gears 34 and 39 are keyed or otherwise firmlyattached to the shaft sleeves 42 and 43 respectively. The sleeve 42moreover is an integral part of propeller shaft assembly 4 as is sleeve43 an integral part of the housing of propeller assembly 3. Inside shaft40 is keyed so as to rotate with sleeve 42 and the same is true of shaft41 with respect to sleeve 43. The keying of these later shafts to thesleeves through which they pass is the expedient which keeps the rackgears 26 in contact with the pinion gears 28 inside the typicalpropeller asan additional slideable freedom used when the propellershafts are simultaneously varied as will be seen under the operationaldescription to follow.

In understanding the operation of the present invention let us assumethat the engine 6 is permitted to idle or operate at some nominal speed.Although a clutch may be provided between the engine and the gearbox 5the system. of the present. invention is. capable of operating very wellwithout the use of a clutch, although clutching would permit easierengine starting. If it is assumed that the steering wheel 25 is=in aneutral position and the lever 13 is essentially in a zero position thecable 1 1 will have pulled the control yoke to its approximatemid-position within the limits of its travel, and both shafts 40 and 41will then be presumed to have positioned the ribbed discs 23 within thepropeller hubs to an approximate mid-position so that the propellerblades are turned so as to afford zero bite. That is to say that theplane of each propeller blade is essentially parallel to the plane ofthe transim 1. the lever 13 is now advanced to oneextreme position suchthat the ribbed discs 23 in both propeller hubs are moved together inthe same direction, the blades of each of the propellers will be pitchedto their nominal maximum (greatest bite). If the engine throttle is nowadvanced to-provide a large amount of power it may be expected that theboat will accelerate very rapidly. Thus it is to be understood that themovement of the lever 13, which in the one extreme gives full forwardandin the other extreme full reverse, operates to advance or retard thecontrol yoke 9 as a unit such that shafts 40 and 41 are withdrawn oradvanced within their respective sleeves 42 and 43 by the same amount.If now the steering wheel 25 is turned some amount in a predetermineddirection, cables 10 and 12 effect differential movements of the shafts40 and41 through the flexible shaft housings in the ends of yokeassembly 9 thereby changing the propeller pitches differentially. As amatter of design, it is possible to provide for extreme turning of thesteering wheel to actually throw one of the two propellers into reversewhile the. other propeller is providing a nearly maximum forward bite.In this way a large force couple in the horizontal plane is appliedessentially at the transom of the boat and the result is very efficientclose-quarter maneuvering.

Thus it will be obvious that the steering wheel 25 is arranged to causedifferential pitching of the blades of either propeller as compared tothe other while the blades of any given propeller all assume the sameangle. Steering is thus a differential thrust proposition.

It will now be apparent that the present invention provides a readymeans for effecting full power braking.

It is believed that it will be obvious to the reader after descriptionto this point that a speeding boat according to the present inventioncould be changed to full power astern simply by full opposite movementof lever 13. No reversing of parts which have significant inertia isnecessary, and no moving part needs even to be slowed during thisprocess. There is moreover no need for loss of time because of shiftingof gears or engaging or disengaging of clutches etc.

Concerning materials, it will be readily apparent that the engine, boathull, steering wheel, and other control levers and cables would normallybe made of conventional materials commonly used for these elements. Thegear box 5, the yoke 9 and various other associated members within theboat hull would be expected to be made from metals customarily used forparts having similar functions in similar environments. The use of nonmetalic gears in the gear box 5 is of course a possibility but if theinvention is to to be applied with a relatively high horsepower enginenon metalic gears would normally not be considered. The propellersthemselves might easily have their external housings or exteriorcylindrical members constructed from bronze or some other metal or alloywhich is relatively strong, machinable, and or castable and yet strongand relatively resistant to fatigue and corrosive environment such asencountered in salt water. The blades would preferably be made of a verystrong and non corrosive material such as stainless steel, since itisimportant that their crosssections be comparatively thin withoutsacrificing strength. The root shaft of each blade would normally bemade of the same stainless steel also, especially where high enginepower is involved.

The gears, of which 28 is typical, within the propeller housing shouldbe understood to afford only one means for pitch adjustment. Thoseskilled in mechanical arts will realize that a crank arm arrangement orsome other mechanical configuration could be substituted.

Many other modifications and variations falling within the scope of thepresent invention will suggest themselves to those skilled in thesearts, and accordingly, it is not intended that the invention be regardedas limited to the embodiment illustrated. The drawings are to beregarded as illustrative only.

What is claimed is:

1. A propulsion and control system for a minimum drag planing hullcomprising the combination of: a pair of outboard stern-mountedcounter-rotating propellers each having a hub and a plurality ofvariable pitch blades, said propellers being mounted so that duringplaning said propellers are in water contact substantially only to adepthnot exceeding the length of any of said blades and said hubs aresubstantially out of water contact; means for supplying mechanical powerto said propellers in such a way as to cause said counter-ro'ta- 7 tion;first pitch control means for controlling the pitch of said bladesdifferently to vary the thrust contribution of each of said propellersand thereby to provide steering control; and second pitch control meansfor controlling the pitch of said blades together and in the same sense,thereby to effect speed control and control between forward and reverse.

2. The invention set forth in claim 1 further defined in that saidblades are all of uniform size and shape.

3. The invention set forth in claim 1 further defined in that said firstand second pitch control means both include means for maintaining all ofthe blades of each propeller always in the same sense and at the samepitch angle.

4. The invention set forth in claim 1 further defined in that each ofsaid propellers includes means for maintaining all of its blades atsubstantially the same pitch angle and for varying the blade pitches ofeach of said propellers uniformly, said means including a pinion gearaffixed to the shaft of each blade, and a gear rack in contact with eachof said pinion gears, said gear racks being structurally integral witheach other.

5. An inboard power boat propulsion and control system comprising: Apair of propellers mounted at the rear of said boat on respective shaftsprotruding through the transom of said boat, said propellers eachcomprising a hub assembly and a plurality of variable pitch blades, saidshafts being so mounted as to position said propellers with respect tothe surface of the water so that substantially only said blades are inwater contract as said propellers turn and said hubs remainsubstantially above said surface of the water; means for supplyingmechanical power to said propellers in a manner so as to cause clockwiserotation of one of said propellers and counterclockwise rotation of theother; means for varying the pitch of the said blades of one of saidpropellers in a first sense while simultaneously varying the pitch ofthe blades of the other of said propellers in the opposite sense tocontrol the direction of the net propulsion force vector thereby toeffect steering of said boat; and means for varying the pitch of thesaid blades of both of said propellers simultaneously in the same sense,thereby to control the magnitude and sense of the propulsion forcevector parallel to the bow-stern axis of the boat.

1. A propulsion and control system for a minimum drag planing hullcomprising the combination of: a pair of outboard sternmountedcounter-rotating propellers each having a hub and a plurality ofvariable pitch blades, said propellers being mounted so that duringplaning said propellers are in water contact substantially only to adepth not exceeding the length of any of said blades and said hubs aresubstantially out of water contact; means for supplying mechanical powerto said propellers in such a way as to cause said counter-rotation;first pitch control means for controlling the pitch of said bladesdifferently to vary the thrust contribution of each of said propellersand thereby to provide steering control; and second pitch control meansfor controlling the pitch of said blades together and in the same sense,thereby to effect speed control and control between forward and reverse.2. The invention set forth in claim 1 further defined in that saidblades are all of uniform size and shape.
 3. The invention set forth inclaim 1 further defined in that said first and second pitch controlmeans both include means for maintaining all of the blades of eachpropeller always in the same sense and at the same pitch angle.
 4. Theinvention set forth in claim 1 further defined in that each of saidpropellers includes means for maintaining all of its blades atsubstantially the same pitch angle and for varying the blade pitches ofeach of said propellers uniformly, said means including a pinion gearaffixed to the shaft of each blade, and a gear rack in contact with eachof said pinion gears, said gear racks being structurally integral witheach other.
 5. An inboard power boat propulsion and control systemcomprising: A pair of propellers mounted at the rear of said boat onrespective shafts protruding through the transom of said boat, saidpropellers each comprising a hub assembly and a plurality of variablepitch blades, said shafts being so mounted as to position saidpropellers with respect to the surface of the water so thatsubstantially only said blades Are in water contract as said propellersturn and said hubs remain substantially above said surface of the water;means for supplying mechanical power to said propellers in a manner soas to cause clockwise rotation of one of said propellers andcounterclockwise rotation of the other; means for varying the pitch ofthe said blades of one of said propellers in a first sense whilesimultaneously varying the pitch of the blades of the other of saidpropellers in the opposite sense to control the direction of the netpropulsion force vector thereby to effect steering of said boat; andmeans for varying the pitch of the said blades of both of saidpropellers simultaneously in the same sense, thereby to control themagnitude and sense of the propulsion force vector parallel to thebow-stern axis of the boat.